GCD 3022 1st Edition Lecture 6 Outline of Last Lecture I Multiple Choice II Law of Independent Assortment III Probability Rule IV True Breeding V Test Cross VI Chi Square Test VII Law of Independent Assortment vs Law of Segregation VIII Chi Square Test IX Product Rule and Binomial Expansion Equation Outline of Current Lecture I Mitosis a Description b Diploid Cells c Phases II Meiosis a Description III The Chromosome a Definition These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute b Locus c Chromatids d Formation of Chromosomes IV Chromosome Theory of Inheritance a Mendel s Law of Segregation b Mendel s Law of Independent Assortment V Cytogenetics a Definition b Karyotypes c Spectral karyotyping VI Human Sex Determination VII X Linked Inheritance a Description b Punnett Squares Current Lecture I II III Mitosis a Mitosis production of two diploid or 2n daughter cells having the same complement of chromosomes as the mother cell b Each daughter cell receives the same complement of chromosomes daughter cells are genetically identical c The phases of mitosis that are emphasized in this course are the S phase DNA replication and the M phase when the cells divide Meiosis a Meiosis production of 4 daughter cells gametes with half the amount of genetic material as the parents haploid or n b Daughter cells are not genetically identical and contain only one homologous chromosome from each pair c Gametes contain many different combinations of the single homologs The Chromosome IV V VI VII a Definition a chromosome is a column of tightly coiled DNA that contains locations of genes two chromosomes create a homologous pair b Locus the location of specific genes on a chromosome c Chromatids the name given to a pair of duplicated chromosomes forms an X shape these are called sister chromatids when connected in the middle by a centromere d Formation of Homologous Pairs pairs sister chromatids are formed by joining two copies of the same chromosome duplicated during S phase of mitosis a pair of sister chromatids 2 X s is called tetrad or bivalent The Chromosome Theory of Inheritance a Mendel s Law of Segregation this law can be explained by the homologous pairing and segregation of chromosomes during meiosis each haploid daughter cell has one allele segregation of alleles into separate gametes b Mendel s Law of Independent Assortment this law can be explained by the relative behavior of different non homolgous chromosomes during meiosis each character contributes one allele to the gamete so that each gamete contains an allele chromosome that has been segregated independently Cytogenetics a Cytogenetics the field of genetics that involves the microscopic examination of chromosomes most often used in the application of chromosome mapping to detect mutations or genes that cause genetic diseases b Karyotype A map of all the chromosome pairs in an individual using dyes each pair of chromosomes can be evaluated to determine which allele an individual has for certain characters c Spectral Karyotyping SKY a type of karyotyping that dyes each pair of chromosomes a different color to more easily separate them arrange them into pairs Human Sex Determination a Humans have 46 chromosomes total 44 autosomes and 2 sex chromosomes b Males have one X and one Y chromosome heterogametic c Females have two X chromosomes homogametic d The Y chromosome determines maleness X Linked Inheritance a When a gene is linked to the X chromosome b This way if a male possesses a dominant X linked trait then all daughters will exhibit that trait because all female offspring receive an X chromosome from their father c X linked traits can be mapped for probability using Punnett squares as long as you make sure to cross a male and female XY x XX d Test Crosses are common when determining X linked inheritance patterns These test crosses are usually used to determine if the female is homozygous or heterozygous for the dominant trait She is mated with a homozygous recessive male and if all offspring exhibit the dominant wild type trait then the mother is homozygous dominant because she passes a dominant X linked trait to every offspring
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